No, there is a waiting period for maternity related cover.
From Quinn Health:
What are waiting periods?
A waiting period is the length of time you need to have health insurance before you can make a claim.
If you are transferring to QUINN-healthcare directly from another Irish health insurer and you have served all of your waiting periods, you will be covered immediately.
If however you are taking out health insurance for the first time, the following waiting periods will apply.
Maternity waiting period: (This is how long you need to wait before you can avail of the maternity grant) 1 year
You are already pregnant and you wish to improve your cover, how long before you can avail of better cover? 1 year